Tests of older baseballs showed that when dropped 24ft onto a concrete surface, they bounced an average of 235.8cm. In a test of 40 new baseballs, the bounce had a mean of 235.4cm. Assume the standard deviation of the bounce for the older baseballs is 4.2cm. Test the claim that the new baseballs have a different mean bounce than the older baseballs. Use a significance level of 0.05. What is the null hypothesis?
1) The null hypothesis is that the mean bounce of the new baseballs is equal to the mean bounce of the older baseballs.
2) The null hypothesis is that the mean bounce of the new baseballs is greater than the mean bounce of the older baseballs.
3) The null hypothesis is that the mean bounce of the new baseballs is less than the mean bounce of the older baseballs.
4) The null hypothesis is that the mean bounce of the new baseballs is not equal to the mean bounce of the older baseballs.